The oyster's biggest pearl theory was discussed after fishermen trawled up the shell near the Solent strait, which separates mainland England from the Isle of Wight. After they cleared the mud off, they found the stone shell to be 10 times the size of a normal oyster, putting a potential pearl inside at thousands and thousands of dollars in value.

"It was discovered in the nets of a fishing boat which was dredging here in the Solent," the Blue Reef Aquarium, who now has the oyster fossil, told Daily Mail. "When the fisherman came back to port they thought it was real, but when they picked it up, cleaned it, and had a closer look they could tell it was a fossil. It had completely turned to stone."

The way the aquarium came across the valuable find was a bit of luck of their part.

"A member of the public called and informed us it was on display at a local fishmongers so we called them and they gave it to us to have in the aquarium," said a representative.

Aquarium representatives suggested that the age of the fossil could be known because of the rings around the shell- that's how the number 100 million years was originally thought of.

"Oysters can be aged by annual growth rings and we have counted more than 200 rings on this oyster making it an extremely long-lived individual," Blue Reef Aquarium said.

Because the shell is stone, however, the fishermen gave the oyster to the Blue Reef Aquarium, who will then use MRI machines to find if the seven-inch wide fossilized shell holds a valuable pearl. Still, the experts there believe there is a "million-to-one chance" that there is a pearl inside after all this time.